According to the 1982 report of the Surgeon General smokers are 10 times more likely to die from lung cancer than are non-smokers. Epidemiological studies have shown an increased risk of oral cancer in snuff-dippers. There are an estimated 7,000,000 snuff-dippers in the United States with the number growing rapidly. In the last decade extensive studies in our laboratory and others have demonstrated the presence of two carcinogenic tobacco specific N-nitrosamines, N'-nitrosonornicotine (NNN) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). NNN and NNK are present in cigarette smoke at 0.11-3.7 Mug/cigarette. Tobacco specific nitrosamines are the only known carcinogens isolated in significant amounts from snuff tobacco (210-33,000 ppb for NNN and NNK). Animal studies have shown NNN and NNK to be potent carcinogens and NNK to be a particularly potent lung carcinogen. NNN and NNK have also been shown to aklylate DNA. In order to study further the relationship between exposure to NNN and NNK and the development of tobacco related cancer, an assay for tobacco specific DNA adducts is needed. Since sensitive immunoassays for a number of carcinogen DNA adducts have been developed, the specific aims of this proposal are 1) develop monoclonal antibodies specific for NNN and NNK-DNA adducts, 2) develop an immunoblotting assay (using these monoclonal antibodies) able to detect low levels of DNA adducts in small samples of human DNA, and 3) demonstrate the applicability of this assay by determining the level of tobacco specific nitrosamine DNA adducts in DNA isolated from the oral mucosa of snuff-dippers. The long term goal of this proposal is to develop methodology of sufficient sensitivity and simplicity that it can be applied by clinical chemists to large numbers of tobacco users. This could allow detection of those individuals at increased risk of developing tobacco related cancer.